[Supraventricular tachyarrhythmias during acute myocardial infarction: short- and mid-term clinical significance, therapy and prevention of relapse]

Abstract

Clinical significance, short and long-term prognostic value, and treatment of supraventricular tachyarrhythmias were evaluated in 208 patients with definite acute myocardial infarction (AMI). No patient received thrombolytic therapy. In Coronary Care Unit supraventricular tachyarrhythmias were detected by continuous electrocardiographic monitoring in 30 (14%) patients: 18 had atrial fibrillation, 1 atrial flutter, 9 paroxysmal atrial tachycardia and 2 non-paroxysmal junctional tachycardia. These episodes began within the first 48 hours of AMI in 93% of patients, and generally they were preceded by frequent or repetitive atrial premature beats. Supraventricular tachyarrhythmias were significantly associated with older age, higher incidence of overt left ventricular dysfunction (both p less than 0.05) and higher Peel Index (p less than 0.02). They caused severe hemodynamic consequences in 20% of patients. In 8 patients they were selflimiting, in 20 they were suppressed by means of medical therapy and in one by DC countershock. During hospitalization supraventricular tachyarrhythmias recurred in one patient; moreover, in this period cardiac death occurred in 26% of patients with supraventricular tachyarrhythmias and in 13% of the remaining (p: ns). Multivariate analysis showed that supraventricular tachyarrhythmias are not important factors in identifying patients at risk of cardiac death. At hospital discharge, patients with supraventricular tachyarrhythmias showed significantly higher values of left ventricular end-diastolic and end-systolic dimensions (both less than 0.05), and a greater use of digitalis-diuretics and/or vasodilators (p less than 0.03). By contrast, in patients with and without supraventricular tachyarrhythmias no significant difference was present with regard to the frequency of New York Heart Association functional classes III-IV for congestive heart failure, frequency of significant tachyarrhythmic events during 24-hour continuous electrocardiographic recording, X-ray cardiac size and left ventricular ejection fraction at rest. In the 2 years following AMI, survival curves showed no significant difference in the risk of cardiac death among patients with or without supraventricular tachyarrhythmias; in particular, in the first group only 2 patients had severe hemodynamic events and no patient showed recurrences of tachyarrhythmia. Our findings suggest that although supraventricular tachyarrhythmias complicating AMI frequently occur in patients with severe cardiac disease they are not related to a higher risk of cardiac death either during in-hospital period or in the 2 years following AMI; medical therapy is effective and safe to suppress these arrhythmias; a systematic use of specific antiarrhythmic drugs to prevent their recurrences is not necessary.